Gusseted type bags

ABSTRACT

A bag of tubular form comprising a plurality of contiguous plies of flexible sheet material, said bag having a front surface and an oppositely disposed rear surface adapted to overlap said front surface at one end of said tube when said bag is in its assembled condition, said bag being longitudinally and reversely creased along diametrically opposed portions to provide a pair of oppositely disposed gussets interposed between said front and rear surfaces, each of said gussets having a front portion and stepped rear portion adapted to overlap said front portion within the overlapped area of said front and rear surfaces at said end of the tube when said bag is in its assembled condition, a bonding agent in a dormant state substantially covering said exposed surfaces at said end of the tube when said bag is in its assembled condition, and said bonding agent being reactivatable to close said bag end, the opposite end of said tube being the reverse of said one end and being folded over and adhered to a surface of said tube by means of said bonding agent, the innermost ply being preferably of a heat sealable material.

United States Patent 1 1 Goodrich et al.

[ GUSSETED TYPE BAGS [75] Inventors: John J. Goodrich, Pensacola, Fla.;

Chester E. Waxlax, New City, N.Y.

[73] Assignee: St. Regis Paper Company, New

York, NY.

[22] Filed: May 26, 1972 [21] App]. No.: 257,253

Related US. Application Data [62] Division of Ser. No. 467,416, June 28,1965, Pat. No.

Primary Examiner-Donald F. Norton Attorney-Raymond J. McElhannon [57]ABSTRACT A bag of tubular form comprising a plurality of contiguousplies of flexible sheet material, said bag having a front surface and anoppositely disposed rear surface adapted to overlap said front surfaceat one end of said tube when said bag is in its assembled condition,said bag being longitudinally and reversely creased along diametricallyopposed portions to provide a pair of oppositely disposed gussetsinterposed between said front and rear surfaces, each of said gussetshaving a front portion and stepped rear portion adapted to overlap saidfront portion within the overlapped area of said front and rear surfacesat said end of the tube when said bag is in its assembled condition, abonding agent in a dormant state substantially covering said exposedsurfaces at said end of the tube when said bag is in its assembledcondition, and said bonding agent being reactivatable to close said bagend, the opposite end of said tube being the reverse of said one end andbeing folded over and adhered to a surface of said tube by means of saidbonding agent, the innermost ply being preferably of a heat scalablematerial.

6 Claims, 15 Drawing Figures PATENTEDDEC 41873 SHEET 2 BF d IIIII I(III:

GUSSETED TYPE BAGS This application is a division of copendingapplication Ser. No. 467,416, filed June 28, 1965 (now U.S. Pat. No.3,687,356

The invention pertains to improvements in gusseted bags of the so-calledpinch bottom type. Gusseted bags constructed in accordance with theinvention may be fabricated from flexible sheet material, such as paperof the like and find wide use in protecting many different types ofcommodities during transit.

The invention pertains more-particularly to a bag of tubular formcomprising a plurality of contiguous plies of flexible sheet materialwherein the bag has a front surface and an oppositely disposed rearsurface which is adapted to overlap the front surface at one end of thetube when the bag is in its assembled condition. The bag islongitudinally and reversely creased along diametrically opposedportions in order to provide a pair of oppositely disposed gussets whichare interposed between the front and rear surfaces. Each of the gussetshas a front portion and a stepped rear portion which is adapted tooverlap the front portion within the overlap area of the front and rearsurfaces at the end of the tube when the bag is in its assembledcondition.

The invention has as one of its aims, the provision of a new andimproved gusseted type bag which has greatly superior closure strengthand bonding characteristics as compared to practices of the prior art;and which controls contamination and insect infestation.

The invention provides as another of its aims, a bag closure which is ofsimple and inexpensive construction and which when completed positivelyseals the bag mouth against leakage and sifting even though the bags areroughly handled in transit. Such gusseted bag construction isaccomplished with a minimum of bag material wastage.

Another feature of the invention resides in the provision of a new andimproved gusseted type bag having a heat sealable inner ply of animpervious character which may be heat sealed without having topenetrate all of the plies of the bag with heat, and which is also ofsuperior strength characteristics ,by means of overlapping the insideply and thereby obtaining a better bond with additional strength. Such astructure is useful for retaining liquids or gases within or without thebag.

The invention provides as another of its aims, a gusseted type bag ofthe character aforesaid having a greatly simplified bag which may besimply closed and sealed in the packer's factory without the necessityof applying additional adhesive material and without excessive adhesiveflowing over the wrong portions of the package, and which simplifies thehandling and filling of the bag by the packer as well as simplifying theopening procedure for the ultimate consumer.

As still another feature of the present invention, a new and improvedgusseted type bag is provided which has a more pleasing appearance andfewer wrinkles and which can still maintain asatisfactory marketablepackage even when there is slight deviation in the fold line as well asdeviations in the bonding agent application.

According to one form of the invention the innermost ply of the gussetedtype bag is fabricated from a heat sealable material. The rear surfaceof the innermost ply is cut substantially flush with the stepped rearportion of the other plies and the front surface of the innermost ply iscut substantially flush with the front portion of the other plies at theend of the tube when the bag is in its assembled condition.

The invention may be embodied in bags of single wall or multi-wallconstruction. As applied to multi-wall bags, further improvements of theinvention are obtained by successively stepping the successive plies atthe bag ends, and/or by similarly successively stepping the plies inonly the gusseted portions of the bag. In this way, upon forming the bagclosure by folding over the bag end and adherently bonding against oneof the bag surfaces, all of the bag plies participate and contribute tothe bonding action.

In accordance with a further aspect of the invention, a bonding agent ina dormant state is applied to the surfaces of the gusset portions aswell as the front and rear surfaces at the end of the tube when the bagis in its assembled condition. The bonding agent is such that it may bereactivated to close the bag subsequent to a later bag fillingoperation. Further, in a modified form of the invention the bondingagent may be applied in transverse spaced strips on the face of thesteps at the end of the tube. In still another form of the invention,the bonding agent is applied adjacent the upper edges of the steps sothat portions of the gusset may be adhered to the rear surface of thetube. This is particularly advantageous since it eliminates thenecessity for manually tucking in the gussets or corners of the bag,which would otherwise be required after the filling operation.

As another aspect of the invention the longitudinal width of the reargusset exposed surfaces may be substantially less than the width of therear wall exposed surface of the front gusset exposed surfaces.

Still another aspect of the present invention resides in the provisionof a new and improved gusseted type bag having a free floatingpolyethylene inside ply. This provides a moisture and air imperviousinner ply which may expand or contact without encountering adversetension or compression forces normally accompanying inter-bonded plies.

Also, according to the present invention a thumb notch may be providedin the outside ply of the front surface adjacent the top edge of therear surface when the rear surface is folded over and adhered to thefront surface.

There has thus been outlined rather broadly the more important featuresof the invention in order that the detailed description thereof thatfollows may be better understood, and in order that the presentcontribution to the art may be better appreciated. There are, of course,additional features of the invention that will be described hereinafterand which will form the subject of the claims appended hereto. Thoseskilled in the art will appreciate that the conception upon which thisdisclosure is based may readily be utilized as a basis for the designingof other structures for carrying out the several purposes of theinvention. It is important, therefore, that the claims be regarded asincluding such FIG. 2 is an enlarged perspective view showing details ofthe closure structure according to one form of the invention;

FIG. 3 is a plan view of a blank of flexible sheet material forfabrication into a multi-ply or multi-wall bag;

FIG. 4 is a fragmentary perspective view showing the closure portion ofa gusseted type bag according to a modified form of the invention;

FIG. 5 is a longitudinal sectional view taken substantially along thelines indicated at 55 in FIG. 4;

FIG. 5a is a fragmentary view showing overlapping closure means of theinner most ply;

FIG. 6 is a fragmentary perspective view showing the closure portion ofa gusseted type bag according to the invention after the exposedsurfaces have been folded over in bonded condition;

FIG. 7 is a longitudinal sectional view taken along the line indicatedat 7-7 in FIG. 6 and showing details of the bonding between the exposedsurfaces and the face of the front wall of the bag;

FIG. 8 is a fragmentary perspective view showing a modified form of thegusset structure when the bag tube is in its flattened condition;

FIG. 9 is a fragmentary perspective view similar to FIG. 8, but showingthe gusset structure after the package has been partially opened;

FIG. 10 is a fragmentary elevation showing another modified form of thegusset construction according to the invention;

FIG. 11 is a fragmentary elevation illustrating still another form ofclosure means according to the invention, wherein portions of thegussets are adhered to the rear surface;

FIG. 12 is a perspective view of a gusseted type bag showing the thumbnotch opening means;

FIG. 13 is a perspective view similar to FIG. 12, but illustrating theoperation of the thumb notch opening means; and

FIG. 14 is a perspective view of a modified form of the inventionshowing a multi wall bag construction wherein the bag plies aresuccessively stepped at the bag ends.

In the embodiment of the invention illustrated in FIGS. 1-3, thegusseted type bag is formed from a plurality of contiguous pliesincluding plies 10, 12 and 14, FIG. 3, of flexible sheet material, suchas kraft or other paper. The innermost ply may have a thin plasticcoating of polyethylene or the like, applied to one or both surfacesthereof for moisture proofing. The plies l0, l2 and 14 arelongitudinally stepped as indicated in FIG. 3 so that when the blank isformed into a tubular member the joining of the respective longitudinaledges of each ply will be staggered. It is noted that only one end ofthe bag or tubular structure is shown, however, it is understood thatthe other end of the bag is constructed in a like complementary steppedmanner.

As best seen in FIGS. 1 and 2, the bag has a front wall surface 16 andan oppositely disposed rear wall surface 18 adapted to overlap or extendabove the front surface at one end of the tube when the bag is in itsassembled condition. Referring to FIG. 1, the bag is longitudinallycreased along fold lines 20, 22, 24 and 26, and further, the bag islongitudinally and reversely creased diametrically opposed lines 28 and30, thereby forming a pair of oppositely disposed gussets indicatedgenerally at 32 and 34 which are interposed between the front and rearwalls or surfaces 16 and 18.

Each of the gussets 32 and 34 have a front portion 36 and a stepped rearportion 38, as seen in FIG. 1. The rear portion 38 is adapted to overlapthe front portion 36 within the overlapped area of the front and rearwall surfaces 16 and 18, thereby forming a rear wall exposed surface 40,rear gusset exposed surfaces 42, front gusset exposed surfaces 44, and afront wall exposed surface 46.

Still referring to FIGS. 1 and 2, there is shown a plurality of spacedtransversely extending strips of a bonding agent in a dormant state. Thebonding agent is a pre-applied type of thermoplastic resin adhesive ofany suitable type. While such adhesive could be applied to substantiallycover all of the exposed surfaces at the end of the bag, it ispreferable that it be applied in horizontally, transversely disposed,spaced strips. As seen in FIGS. 1 and 2, a first strip 48 is applied onthe rear wall exposed surface 40 and extends substantially across thewidth of the bag. A second strip extends across the rear gusset exposedsurfaces 42 and preferably across the adjacent portion of the rear wallexposed surface as at 51. Next, a third strip 52 extends across thefront gusset exposed surfaces 44 and preferably across the adjacentportion 53 of the rear wall exposed surface as at 53, and a fourth stripof bonding agent 54 is applied to the front wall exposed surface 46.When packaging certain materials, the strip of bonding agent 54 may bedispensed with, but when packaging other commodities the bonding agentstrip 54 serves a very important function. That is, the latter stripserves to make the bag contamination or insect proof, otherwise there isthe possibility that insects may penetrate through the corners of thebag thereby gaining access to the interior thereof. Moreover, the stripof bonding agent 54 serves as an added measure of protection in theevent that the application apparatus of the strips of bonding agent 48,50 and 52 misfires or skips a spot, the package would nevertheless besatisfactorily sealed.

As best seen in FIGS. 6 and 7, closure of the package is accomplished byfolding the end along the fold crease 56, thus to adhere the bag end tothe outer ply of the front surface 16. As seen in FIG. 7, each of theadhesive strips 48, 50, 52 and 54 are in direct contact with the frontsurface. This is why applicants bag is of substantially superiorstrength as compared to bags of the prior art.

Normally the bags are shipped to the packers in the condition as shownin FIG. 2 with the bonding medium already applied. The packer opens thetop of the bag and inserts a filling spout therein for filling the bagwith a desired commodity. Thereafter, the operators tuck-in the gussetportions and fold over the end of the bag along crease line 56, FIG. 2.Normally heat and pressure are applied to reactivate the preappliedbonding agent to thereby permanently close the bag. This may beaccomplished by means of hot pressure bars or hot rollers, as desired.Also, with certain types of bonding agents, a hot air blast may beemployed to reactivate the bonding agent, or in still other instancesthe bonding agent may require chemical reactivation. It will beappreciated that with the aforementioned type of preapplied bondingagent, the packer is not troubled with the problem of applying adhesiveto the bag in his plant. This may be particularly desirable whenpackaging comestibles wherein adhesive may accidently becomeintermingled with the contents of the package.

Referring to FIGS. 4 and 5, the innermost ply designated generally at 58has a front wall exposed surface 60 which extends beyond the other frontwall plies and a rear wall exposed surface 62 which extends below theother rear wall plies. Preferably the front surface 60 is substantiallyflush with the front gusset exposed sur-v faces 64, and the rear wallexposed surface 62 is flush with the rear gusset surfaces 66. Theinnermost ply 58 is fabricated from heat seal material, and accordingly,the exposed surfaces thereof may be subjected to heat and thereby sealedwithout the necessity of the heat passing through as many plies as wouldbe necessary if the inner ply was of the same relative height as theouter plies. Further, the inner ply 58 may be fabricated from manydifferent types of materials porous and nonporous. For example, suchmaterials include polyolefines such as polyethylene and polypropylene,polyamides such as nylon and polyesters such as polyalkylene derivativesof polycarboxylic acids especially polyethylene terephthlite. Further,the inner ply may be fabricated into a tubular member in a suitablemanner such as that disclosed in copending US. Pat. application Ser. No.430,417, filed Feb. 4, I965 (now US. Pat. No. 3,399,096.

If the inner ply 58 is thermoplastic coated then, as best seen in FIG.a, the rear wall 62 of the inner ply 58 may be doubled over upon itselfand the front wall surface 60 overlapped thereover in order to form ahermetic seal between the two thermoplastic surfaces.

Referring to FIGS. 8 and 9, there is illustrated a modified form ofgusset construction. In this form a front gusset surfaces 68 and a reargusset surface 70 are cut to substantially the same height or flush, andboth are disposed within the overlapped area of the rear wall exposedsurface 40 and the front wall exposed surface 46. Further, according tothis form of the invention, the top edge of the front and rear gussetexposed surfaces 68 and 70 are serrated or are provided with diamond orround notching as indicated at 72. The first transverse strip of bondingagent 74 is applied across the rear wall exposed surface 40, and asecond transverse strip of bonding agent is applied across the top edgeof the gussets including the serrated edge portion 72, thereby adheringboth the front and back gussets 68 and 70 to the rear wall 40 at the topof the bag. This has the advantage of preventing leakage of packagingmaterial at the outer extremities of the gussets, and also facilitatesclosure of the bag after filling with packaging material since iteliminates the necessity for manually tucking in the corners of thegussets which would otherwise be required.

Referring to FIG. 10, there is illustrated a modified form of gussetarrangement wherein three strips of preapplied bonding agent in adormant state are applied to the rear wall exposed surface, to the reargusset exposed surfaces and to the front gusset exposed surfacesrespectively. That is, one strip of bonding agent 78 is appliedtransversely of the bag across the rare wall exposed surface 76; asecond strip 80 of bonding agent is applied to the upper edge of therear gusset exposed surface 82 so that a portion of the bonding agentappears on the top edge of the rear gusset exposedsurface 82 and aportion of the bonding agent appears on the adjacent portion of the rearwall exposed surface 76, thereby bonding the two surfaces together alongthe line 84 as well as along the line 86; and a third strip 88 ofbonding agent is applied along the top edge of the front gusset exposedsurface 90 in an overlapping manner as seen in FIG. 10 so that the frontgusset exposed surface 90 is bonded to the rear gusset exposed surface82 along the line 92 and the front gusset surface 90 is also bonded tothe rear wall exposed surface 76 along the line 94. As pointed outabove, bonding of the gussets one to the other and to the rear wallserves to prevent leakage of the packaging material at the extremitiesof gussets and facilitates closure of the bag after filling withpackaging material.

Referring next to FIG. 11, there is illustrated a further modificationof the invention. According to this embodiment, the front gusset exposedsurface is stepped below the rear gusset exposed surface and the upperedges of both gusset surfaces are provided with a serrated or sawtoothtype contoured edge as indicated at 96 and 98, respectively. Thisconstruction provides a longer effective linear edge for providingbetter bonding characteristics between the front gusset 90 and the reargusset 82 as well as the rear gusset 82 and the rear wall exposedsurface 76.

Referring to FIGS. 12 and 13, there is shown new and improved means foropening a gusseted type bag. A thumb notch 100 is formed in theoutermost ply of a multi-ply bag by an interrupted line of slit 102therein disposed adjacent the top edge of the rear wall 18 when the rearwall is folded over in sealed condition. Since the aforementioned stripsof adhesive material are adhered to the outermost ply of the front wall16, the thumb notch 100 tends to rip the outermost ply of the front wall16 underneath the folded over portion of the back wall 18, and therebyprovides a thumb grip to grasp the so-folded over back wall that it canbe easily lifted to open the bag as shown in FIG. 13.

Referring to the multi-wall bag constructions, the bag plies may besuccessively stepped at the bag ends to provide additional adherence onforming the bag closure. Thus, referring to FIG. 14, the rear wallexposed surface comprises a plurality of plies which may, for example,include three plies including an outside ply 104, a second ply 106 andan inside ply 108. The rear gusset exposed surfaces include an outsideor first ply 110, a second ply l 12 and aninside or third ply l 14. Thefront gusset exposed surfaces include plies 1 16, 118 and 120. The frontwall exposed surface includes a first ply 122, a second ply 124 and athird ply or inside ply 126. It will be appreciated that each of theplies in eachof the exposed surfaces has a bonding agent in a dormantstate applied thereto as at 128, FIG. 14. The bonding agent isreactivat'able to permanently close the bag subsequent to a later bagfilling operation. In this way, portions of all the bag plies in allsurfaces including the gusset areas, upon formingthe bag closure byfolding over along the fold line and reactivating the bonding agent, areadherently bonded to the bag surface.

It will be understood that various changes in the details, materials andarrangements of parts which have been herein described and illustratedin order to explain the nature of the invention, may be made by thoseskilled in the art within the principle and scope of the invention, asexpressed in the appended claims.

What is claimed is l. A bag of tubular form comprising a plurality of atleast three contiguous plies of flexible sheet material, said bag havinga front surface and an oppositely disposed rear surface adapted tooverlap said front surface at one end of said tube when said bag is inits assembled condition, said bag being longitud-inally and reverselycreased along diametrically opposed portions to provide a pair ofoppositely disposed gussets interposed between said front and rearsurfaces, each of said gussets having an exposed front portion and anexposed rear portion which is stepped above said front portion andadapted to overlap said front portion within the overlapped area of saidfront and rear surfaces at said end of the tube when said bag is in itsassembled condition, at least some of the bag plies being stepped insaid front and rear surface portions to provide exposed portionsthereof, a heat reactive bonding agent in a dormant state substantiallycovering said exposed gusset portions and front and rear surfaceportions at said end of the tube when said bag is in its assembledcondition, and said bonding agent being reactivatable to close said bagend, the opposite end of said tube being the reverse 8. of said one endand being folded over and adhered to a surface of said tube by means ofsaid bonding agent.

2. A bag according to claim 1 having an inner ply composed of a moistureimpervious material. 7

3. A bag according to claim 1 in which at least the inner surface of theinnermost ply of which is provided with a moisture resistant surface.

4. A bag according to claim 1, the innermost ply of which is comprisedof a heat sealable plastic material.

5. A bag according to claim 4 wherein the opposed walls of saidinnermost ply are heat sealed to one another at said folded over end ofsaid bag.

6. A bag according to claim 5 wherein said heat sealed end of saidinnermost ply is freely displaceable with respect to the remaining plysat said folded over end of said bag.

1. A bag of tubular form comprising a plurality of at least threecontiguous plies of flexible sheet material, said bag having a frontsurface and an oppositely disposed rear surface adapted to overlap saidfront surface at one end of said tube when said bag is in its assembledcondition, said bag being longitud-inally and reversely creased alongdiametrically opposed portions to provide a pair of oppositely disposedgussets interposed between said front and rear surfaces, each of saidgussets having an exposed front portion and an exposed rear portionwhich is stepped above said front portion and adapted to overlap saidfront portion within the overlapped area of said front and rear surfacesat said end of the tube when said bag is in its assembled condition, atleast some of the bag plies being stepped in said front and rear surfaceportions to provide exposed portions thereof, a heat reactive bondingagent in a dormant state substantially covering said exposed gussetportions and front and rear surface portions at said end of the tubewhen said bag is in its assembled condition, and said bonding agentbeing reactivatable to close said bag end, the opposite end of said tubebeing the reverse of said one end and being folded over and adhered to asurface of said tube by means of said bonding agent.
 2. A bag accordingto claim 1 having an inner ply composed of a moisture imperviousmaterial.
 3. A bag according to claim 1 in which at least the innersurface of the innermosT ply of which is provided with a moistureresistant surface.
 4. A bag according to claim 1, the innermost ply ofwhich is comprised of a heat sealable plastic material.
 5. A bagaccording to claim 4 wherein the opposed walls of said innermost ply areheat sealed to one another at said folded over end of said bag.
 6. A bagaccording to claim 5 wherein said heat sealed end of said innermost plyis freely displaceable with respect to the remaining plys at said foldedover end of said bag.